Researches on a Fractal Watermarking Algorithm Based on Luminance Shifting Factor

A new fractal watermarking algorithm is proposed, in which the watermark embedded can be extracted well. To achieve high-quality extracted watermark under some image attacks, the algorithm selects a suitable image arbitrarily and performs fractal encoding for the image. Then the image is decoded after the watermark image takes the place of the luminance shifting factor in the fractal codebook. Finally according to sub-block DCT watermarking algorithm, the decoded binary image is embedded into the DCT middle frequency coefficients of the original image to obtain the watermarked image. Experimental results demonstrate the good robustness and invisibility of our approach proposed.